Biological Classification Class 11 Notes Biology Chapter 2

 Page 1


Points to Remember
Systems of Classification :
? Earliest	 classification 	 was	 given	 by	 Aristotle.	 Divided	 plants	 into	 herbs,
shrubs	and	trees.
Animals	into	those	with	red	blood	and	those	who	do	not	have	it.
? Two kingdom classification : Given	 by	 Carolous	 Linneaeus–Kingdom–
plantae	and	kingdom–Animalia.
? Five kingdom classification : By	 R.H.	 Whittaker ,	 Monera,	 Protista,	 Fungi,
Plantae	and	 Animalia	are	the	five	kingdoms.
? The	 main	 criteria	 for	 classification	 of	 or ganisms	 into	 five	 kingdoms	 include
cell	 structure ,	 thallus	 or ganisation,	 mode	 of	 nutrition,	 reproduction	 and
phylogenetic	relationships.
Kingdom Monera :
? Has	bacteria	as	sole	members.
? Bacteria	 can	 have	 shapes	 like	 :	 Coccus	 (spherical),	 Bacillus	 (rod-shaped),
V ibrium	(comma	shaped)	and	spirillum	(spiral	shaped).
? Bacteria	 found	 almost	 everywhere	 and	 can	 be	 Photosynthetic	 autotrophs,
Chemosynthetic	autotrophs	or	Heterotrophs.
Archaebacteria
Bacteria
Eubacteria
Page 2


Points to Remember
Systems of Classification :
? Earliest	 classification 	 was	 given	 by	 Aristotle.	 Divided	 plants	 into	 herbs,
shrubs	and	trees.
Animals	into	those	with	red	blood	and	those	who	do	not	have	it.
? Two kingdom classification : Given	 by	 Carolous	 Linneaeus–Kingdom–
plantae	and	kingdom–Animalia.
? Five kingdom classification : By	 R.H.	 Whittaker ,	 Monera,	 Protista,	 Fungi,
Plantae	and	 Animalia	are	the	five	kingdoms.
? The	 main	 criteria	 for	 classification	 of	 or ganisms	 into	 five	 kingdoms	 include
cell	 structure ,	 thallus	 or ganisation,	 mode	 of	 nutrition,	 reproduction	 and
phylogenetic	relationships.
Kingdom Monera :
? Has	bacteria	as	sole	members.
? Bacteria	 can	 have	 shapes	 like	 :	 Coccus	 (spherical),	 Bacillus	 (rod-shaped),
V ibrium	(comma	shaped)	and	spirillum	(spiral	shaped).
? Bacteria	 found	 almost	 everywhere	 and	 can	 be	 Photosynthetic	 autotrophs,
Chemosynthetic	autotrophs	or	Heterotrophs.
Archaebacteria
Bacteria
Eubacteria
? Halophiles	(salt-loving)
? Thermoacidophiles	(in	hot	springs)
? Methanogens 	 (in	 marsh	 and	 in	 gut	 of	 ruminant	 animals.	 Produce	 methane
gas.)
? Photosynthetic	 autotrophs	 like	 Cyanobacteria	 (Blue-green	 algae	 BGA).
Some	 like	Anabaena and Nostoc 	 have	 specialized	 cells 	 called	 heterocysts
for	nitrogen	fixation.
? Algae bloom is	 rich	 growth 	 of	 blue 	 green	 algae 	 over	 the	 surface	 of	 polluted
water	bodies.
? Algae	 bloom	 releases	 neurotoxins,	 deplete	 oxygen	 and	 makes 	 water 	 unfit
for 	use.
? Chemosynthetic autotrophs : Oxidise 	 various	 inor ganic 	 substances 	 like
nitrates/nitrites, 	 ammonia	 and	 use	 released 	 ener gy 	 for	 their 	 A TP 	 proudction.
They	helps 	in	nutrients	recycling	of	N,	P ,	Fe	and	S.
? Heterotophic bacteria : Decomposers	 help	 in	 making	 curd, 	 production	 of
antibiotic,	 N
2
	 fixation,	 casuse 	 disesaes	 like 	 cholera,	 typhoid,	 tetan us 	 and
citrus	canker .
Mycoplasmas : Completely 	 lack 	 cell 	 wall. 	 Smallest 	 living 	 cells. 	 Can	 survive
without	oxygen.	Pathogenic 	in	animals	and	plants.
Kingdom PROTISTA
 (Comprises	of	all 	single	celled	eukaryotes)
? Forms	a	link	between	plants,	animals	and	fungi.
(i)	 Chrysophytes (Has	diatoms	and	golden	algae/desmids)
Fresh	water/marine, 	photosynthetic,	microscopic	plankton.
? Chief 	producers 	in	Ocean.
? Cell	 walls	 have	 silica	 which	 makes	 it	 indestructible	 and	 cell	 walls
overlap 	to	fit	together 	like	a	soap	box.
? Their	accumulation 	forms 	‘Diatomaceous 	Earth”	(gritty 	soil)
? Used	in	polishing,	filtration 	of	oils 	and	syrups.
Page 3


Points to Remember
Systems of Classification :
? Earliest	 classification 	 was	 given	 by	 Aristotle.	 Divided	 plants	 into	 herbs,
shrubs	and	trees.
Animals	into	those	with	red	blood	and	those	who	do	not	have	it.
? Two kingdom classification : Given	 by	 Carolous	 Linneaeus–Kingdom–
plantae	and	kingdom–Animalia.
? Five kingdom classification : By	 R.H.	 Whittaker ,	 Monera,	 Protista,	 Fungi,
Plantae	and	 Animalia	are	the	five	kingdoms.
? The	 main	 criteria	 for	 classification	 of	 or ganisms	 into	 five	 kingdoms	 include
cell	 structure ,	 thallus	 or ganisation,	 mode	 of	 nutrition,	 reproduction	 and
phylogenetic	relationships.
Kingdom Monera :
? Has	bacteria	as	sole	members.
? Bacteria	 can	 have	 shapes	 like	 :	 Coccus	 (spherical),	 Bacillus	 (rod-shaped),
V ibrium	(comma	shaped)	and	spirillum	(spiral	shaped).
? Bacteria	 found	 almost	 everywhere	 and	 can	 be	 Photosynthetic	 autotrophs,
Chemosynthetic	autotrophs	or	Heterotrophs.
Archaebacteria
Bacteria
Eubacteria
? Halophiles	(salt-loving)
? Thermoacidophiles	(in	hot	springs)
? Methanogens 	 (in	 marsh	 and	 in	 gut	 of	 ruminant	 animals.	 Produce	 methane
gas.)
? Photosynthetic	 autotrophs	 like	 Cyanobacteria	 (Blue-green	 algae	 BGA).
Some	 like	Anabaena and Nostoc 	 have	 specialized	 cells 	 called	 heterocysts
for	nitrogen	fixation.
? Algae bloom is	 rich	 growth 	 of	 blue 	 green	 algae 	 over	 the	 surface	 of	 polluted
water	bodies.
? Algae	 bloom	 releases	 neurotoxins,	 deplete	 oxygen	 and	 makes 	 water 	 unfit
for 	use.
? Chemosynthetic autotrophs : Oxidise 	 various	 inor ganic 	 substances 	 like
nitrates/nitrites, 	 ammonia	 and	 use	 released 	 ener gy 	 for	 their 	 A TP 	 proudction.
They	helps 	in	nutrients	recycling	of	N,	P ,	Fe	and	S.
? Heterotophic bacteria : Decomposers	 help	 in	 making	 curd, 	 production	 of
antibiotic,	 N
2
	 fixation,	 casuse 	 disesaes	 like 	 cholera,	 typhoid,	 tetan us 	 and
citrus	canker .
Mycoplasmas : Completely 	 lack 	 cell 	 wall. 	 Smallest 	 living 	 cells. 	 Can	 survive
without	oxygen.	Pathogenic 	in	animals	and	plants.
Kingdom PROTISTA
 (Comprises	of	all 	single	celled	eukaryotes)
? Forms	a	link	between	plants,	animals	and	fungi.
(i)	 Chrysophytes (Has	diatoms	and	golden	algae/desmids)
Fresh	water/marine, 	photosynthetic,	microscopic	plankton.
? Chief 	producers 	in	Ocean.
? Cell	 walls	 have	 silica	 which	 makes	 it	 indestructible	 and	 cell	 walls
overlap 	to	fit	together 	like	a	soap	box.
? Their	accumulation 	forms 	‘Diatomaceous 	Earth”	(gritty 	soil)
? Used	in	polishing,	filtration 	of	oils 	and	syrups.
	 (ii)	 Dinoflagellates :
? Marine,	photosynthetic, 	cell	wall 	has	stif f	cellulose	plates.
? T wo	 flagella–one	 longitudinal	 and	 other	 transverse 	 in	 a	 furrow
between	wall	plates.
? Example : Gonyaulax multiples rapdily, make sea appear red (red
tides) and produce toxins to kill marine animals.
	 (iii)	 Euglenoids :
? Found	in	stagnant	fresh	water .
Have	protein	rich 	layer 	‘pellicle’ 	which	makes	body	flexible.
? Photosynthetic	 in 	 presence	 of	 sunlight	 but	 become 	 heterotrophs 	 if
they	do	not	get 	sunlight. 	(Mixotrophic	nutrition)
? Example : Euglena
 (iv)	Slime Moulds :
? Saprophytic	protists
? Under	 suitable	 conditions 	 form	 an	 aggregates 	 called	 plasmodium,
grows	on	decaying 	twigs 	and	leaves.
? During	 unfavourable	 conditions,	 plasmodium	 dif ferentiates 	 and
forms	fruiting 	bodies	bearing	spores	at	their	tips.
? Spores 	 have 	 true 	 walls	 which 	 are 	 extremely	 resistant	 and	 survive 	 for
many	years	and	dispersed	by	air	currents.
	 (v)	 Protozoans : 	 Are	 heterotrops 	 and	 live	 as	 parasites.	 Have	 four 	 major	
groups.
Amoeboid : Catc h	 prey	 using	 pseudopodia, 	e.g., Amoeba. Entamoeba 
are	parasite.
Flagellated : Have	 one	 or	 more	 flagella. 	 Cause	 disease	 like 	 Sleepin g	
Sickness	e.g., trypanosoma.
Ciliated : Have	 clilia	 to	 move 	 food	 into	 gullet 	 and	 help	 in	 locomo tion.	
e.g., Paramoecium.
Sporozoans : Have	 infective 	 spore	 like 	 stage	 in	 life	 cycle,	 e.g., 
Plasmodium 	which	causes	malaria.
Page 4


Points to Remember
Systems of Classification :
? Earliest	 classification 	 was	 given	 by	 Aristotle.	 Divided	 plants	 into	 herbs,
shrubs	and	trees.
Animals	into	those	with	red	blood	and	those	who	do	not	have	it.
? Two kingdom classification : Given	 by	 Carolous	 Linneaeus–Kingdom–
plantae	and	kingdom–Animalia.
? Five kingdom classification : By	 R.H.	 Whittaker ,	 Monera,	 Protista,	 Fungi,
Plantae	and	 Animalia	are	the	five	kingdoms.
? The	 main	 criteria	 for	 classification	 of	 or ganisms	 into	 five	 kingdoms	 include
cell	 structure ,	 thallus	 or ganisation,	 mode	 of	 nutrition,	 reproduction	 and
phylogenetic	relationships.
Kingdom Monera :
? Has	bacteria	as	sole	members.
? Bacteria	 can	 have	 shapes	 like	 :	 Coccus	 (spherical),	 Bacillus	 (rod-shaped),
V ibrium	(comma	shaped)	and	spirillum	(spiral	shaped).
? Bacteria	 found	 almost	 everywhere	 and	 can	 be	 Photosynthetic	 autotrophs,
Chemosynthetic	autotrophs	or	Heterotrophs.
Archaebacteria
Bacteria
Eubacteria
? Halophiles	(salt-loving)
? Thermoacidophiles	(in	hot	springs)
? Methanogens 	 (in	 marsh	 and	 in	 gut	 of	 ruminant	 animals.	 Produce	 methane
gas.)
? Photosynthetic	 autotrophs	 like	 Cyanobacteria	 (Blue-green	 algae	 BGA).
Some	 like	Anabaena and Nostoc 	 have	 specialized	 cells 	 called	 heterocysts
for	nitrogen	fixation.
? Algae bloom is	 rich	 growth 	 of	 blue 	 green	 algae 	 over	 the	 surface	 of	 polluted
water	bodies.
? Algae	 bloom	 releases	 neurotoxins,	 deplete	 oxygen	 and	 makes 	 water 	 unfit
for 	use.
? Chemosynthetic autotrophs : Oxidise 	 various	 inor ganic 	 substances 	 like
nitrates/nitrites, 	 ammonia	 and	 use	 released 	 ener gy 	 for	 their 	 A TP 	 proudction.
They	helps 	in	nutrients	recycling	of	N,	P ,	Fe	and	S.
? Heterotophic bacteria : Decomposers	 help	 in	 making	 curd, 	 production	 of
antibiotic,	 N
2
	 fixation,	 casuse 	 disesaes	 like 	 cholera,	 typhoid,	 tetan us 	 and
citrus	canker .
Mycoplasmas : Completely 	 lack 	 cell 	 wall. 	 Smallest 	 living 	 cells. 	 Can	 survive
without	oxygen.	Pathogenic 	in	animals	and	plants.
Kingdom PROTISTA
 (Comprises	of	all 	single	celled	eukaryotes)
? Forms	a	link	between	plants,	animals	and	fungi.
(i)	 Chrysophytes (Has	diatoms	and	golden	algae/desmids)
Fresh	water/marine, 	photosynthetic,	microscopic	plankton.
? Chief 	producers 	in	Ocean.
? Cell	 walls	 have	 silica	 which	 makes	 it	 indestructible	 and	 cell	 walls
overlap 	to	fit	together 	like	a	soap	box.
? Their	accumulation 	forms 	‘Diatomaceous 	Earth”	(gritty 	soil)
? Used	in	polishing,	filtration 	of	oils 	and	syrups.
	 (ii)	 Dinoflagellates :
? Marine,	photosynthetic, 	cell	wall 	has	stif f	cellulose	plates.
? T wo	 flagella–one	 longitudinal	 and	 other	 transverse 	 in	 a	 furrow
between	wall	plates.
? Example : Gonyaulax multiples rapdily, make sea appear red (red
tides) and produce toxins to kill marine animals.
	 (iii)	 Euglenoids :
? Found	in	stagnant	fresh	water .
Have	protein	rich 	layer 	‘pellicle’ 	which	makes	body	flexible.
? Photosynthetic	 in 	 presence	 of	 sunlight	 but	 become 	 heterotrophs 	 if
they	do	not	get 	sunlight. 	(Mixotrophic	nutrition)
? Example : Euglena
 (iv)	Slime Moulds :
? Saprophytic	protists
? Under	 suitable	 conditions 	 form	 an	 aggregates 	 called	 plasmodium,
grows	on	decaying 	twigs 	and	leaves.
? During	 unfavourable	 conditions,	 plasmodium	 dif ferentiates 	 and
forms	fruiting 	bodies	bearing	spores	at	their	tips.
? Spores 	 have 	 true 	 walls	 which 	 are 	 extremely	 resistant	 and	 survive 	 for
many	years	and	dispersed	by	air	currents.
	 (v)	 Protozoans : 	 Are	 heterotrops 	 and	 live	 as	 parasites.	 Have	 four 	 major	
groups.
Amoeboid : Catc h	 prey	 using	 pseudopodia, 	e.g., Amoeba. Entamoeba 
are	parasite.
Flagellated : Have	 one	 or	 more	 flagella. 	 Cause	 disease	 like 	 Sleepin g	
Sickness	e.g., trypanosoma.
Ciliated : Have	 clilia	 to	 move 	 food	 into	 gullet 	 and	 help	 in	 locomo tion.	
e.g., Paramoecium.
Sporozoans : Have	 infective 	 spore	 like 	 stage	 in	 life	 cycle,	 e.g., 
Plasmodium 	which	causes	malaria.
Kingdom Fungi
1. Heterotrophic	or ganisms
2. Non 	 chlorpohyllous 	hyphae
3. Network	of	hyphae	called	mycelium
4. Hyphae 	 which	 have	 multinucleated 	 cytoplasm	 are	 called	 coenocytic	 hyphae
5. Cell 	wall	of	chitin	and 	polysaccharides
6. Cosmopolitan. 	Grow 	in	warm 	and	humid	places.
7. Saprophytic, 	 parasitic, 	 symbiotic 	 (Lichen	 and	 Mycorrhiza)	e.g., Puccinia,
(wheat 	rust 	disease), 	Penicillium, Y east 	(unicellular 	fungus).
8. Reproduction 	 can	 take	 place 	 by	 vegetative	 means	 fragmentation,	 fission
and	 budding.	 Asexual 	 reproduction	 by	 spores–conidia, 	 sporangiospores	 or
zoospores. 	 Sexual 	 reproduction 	 by 	 Oospores,	 ascospores 	 and	 basidiospore s–
produced 	in	fruiting	bodies.
9. Sexual cycle involves 3 steps :
 (i)	 Plasmogamy	(fusion 	of	Protoplasms.)
(ii)	 Karyogamy	(fusion	of		two	nuclei.)
(iii)	 Meiosis 	in	zygote	resulting	in	haploid	spores.
10. Dikaryophase 	 is 	 a	 condition	 of	 having	 dikaryon	 in	 an	 intervening 	 dikaryotic
stage 	(n	+	n	i.e., 	 two	 nuclei	 per	 cell) 	 between	 plasmogamy	 and	 karyogamy
in 	fungi	like	ascomycetes 	and	basidiomycetes.
Classes of Fungi
 (i) Phycomycetes :
 ? grow	on	decaying	wood	or	as 	obligate	parasites 	on	plants
 ? Mycelium	aseptate 	and	coenocytic
 ? Spores	produced	endogenously 	in	sporangium.
 ? Asexual 	reproduction 	by	Zoospores 	or	 Aplanospores
 ? Zygospores	are	formed 	by	the	fusion 	of	gametes.
e.g., Rhizopus, Albugo, Mucor
Page 5


Points to Remember
Systems of Classification :
? Earliest	 classification 	 was	 given	 by	 Aristotle.	 Divided	 plants	 into	 herbs,
shrubs	and	trees.
Animals	into	those	with	red	blood	and	those	who	do	not	have	it.
? Two kingdom classification : Given	 by	 Carolous	 Linneaeus–Kingdom–
plantae	and	kingdom–Animalia.
? Five kingdom classification : By	 R.H.	 Whittaker ,	 Monera,	 Protista,	 Fungi,
Plantae	and	 Animalia	are	the	five	kingdoms.
? The	 main	 criteria	 for	 classification	 of	 or ganisms	 into	 five	 kingdoms	 include
cell	 structure ,	 thallus	 or ganisation,	 mode	 of	 nutrition,	 reproduction	 and
phylogenetic	relationships.
Kingdom Monera :
? Has	bacteria	as	sole	members.
? Bacteria	 can	 have	 shapes	 like	 :	 Coccus	 (spherical),	 Bacillus	 (rod-shaped),
V ibrium	(comma	shaped)	and	spirillum	(spiral	shaped).
? Bacteria	 found	 almost	 everywhere	 and	 can	 be	 Photosynthetic	 autotrophs,
Chemosynthetic	autotrophs	or	Heterotrophs.
Archaebacteria
Bacteria
Eubacteria
? Halophiles	(salt-loving)
? Thermoacidophiles	(in	hot	springs)
? Methanogens 	 (in	 marsh	 and	 in	 gut	 of	 ruminant	 animals.	 Produce	 methane
gas.)
? Photosynthetic	 autotrophs	 like	 Cyanobacteria	 (Blue-green	 algae	 BGA).
Some	 like	Anabaena and Nostoc 	 have	 specialized	 cells 	 called	 heterocysts
for	nitrogen	fixation.
? Algae bloom is	 rich	 growth 	 of	 blue 	 green	 algae 	 over	 the	 surface	 of	 polluted
water	bodies.
? Algae	 bloom	 releases	 neurotoxins,	 deplete	 oxygen	 and	 makes 	 water 	 unfit
for 	use.
? Chemosynthetic autotrophs : Oxidise 	 various	 inor ganic 	 substances 	 like
nitrates/nitrites, 	 ammonia	 and	 use	 released 	 ener gy 	 for	 their 	 A TP 	 proudction.
They	helps 	in	nutrients	recycling	of	N,	P ,	Fe	and	S.
? Heterotophic bacteria : Decomposers	 help	 in	 making	 curd, 	 production	 of
antibiotic,	 N
2
	 fixation,	 casuse 	 disesaes	 like 	 cholera,	 typhoid,	 tetan us 	 and
citrus	canker .
Mycoplasmas : Completely 	 lack 	 cell 	 wall. 	 Smallest 	 living 	 cells. 	 Can	 survive
without	oxygen.	Pathogenic 	in	animals	and	plants.
Kingdom PROTISTA
 (Comprises	of	all 	single	celled	eukaryotes)
? Forms	a	link	between	plants,	animals	and	fungi.
(i)	 Chrysophytes (Has	diatoms	and	golden	algae/desmids)
Fresh	water/marine, 	photosynthetic,	microscopic	plankton.
? Chief 	producers 	in	Ocean.
? Cell	 walls	 have	 silica	 which	 makes	 it	 indestructible	 and	 cell	 walls
overlap 	to	fit	together 	like	a	soap	box.
? Their	accumulation 	forms 	‘Diatomaceous 	Earth”	(gritty 	soil)
? Used	in	polishing,	filtration 	of	oils 	and	syrups.
	 (ii)	 Dinoflagellates :
? Marine,	photosynthetic, 	cell	wall 	has	stif f	cellulose	plates.
? T wo	 flagella–one	 longitudinal	 and	 other	 transverse 	 in	 a	 furrow
between	wall	plates.
? Example : Gonyaulax multiples rapdily, make sea appear red (red
tides) and produce toxins to kill marine animals.
	 (iii)	 Euglenoids :
? Found	in	stagnant	fresh	water .
Have	protein	rich 	layer 	‘pellicle’ 	which	makes	body	flexible.
? Photosynthetic	 in 	 presence	 of	 sunlight	 but	 become 	 heterotrophs 	 if
they	do	not	get 	sunlight. 	(Mixotrophic	nutrition)
? Example : Euglena
 (iv)	Slime Moulds :
? Saprophytic	protists
? Under	 suitable	 conditions 	 form	 an	 aggregates 	 called	 plasmodium,
grows	on	decaying 	twigs 	and	leaves.
? During	 unfavourable	 conditions,	 plasmodium	 dif ferentiates 	 and
forms	fruiting 	bodies	bearing	spores	at	their	tips.
? Spores 	 have 	 true 	 walls	 which 	 are 	 extremely	 resistant	 and	 survive 	 for
many	years	and	dispersed	by	air	currents.
	 (v)	 Protozoans : 	 Are	 heterotrops 	 and	 live	 as	 parasites.	 Have	 four 	 major	
groups.
Amoeboid : Catc h	 prey	 using	 pseudopodia, 	e.g., Amoeba. Entamoeba 
are	parasite.
Flagellated : Have	 one	 or	 more	 flagella. 	 Cause	 disease	 like 	 Sleepin g	
Sickness	e.g., trypanosoma.
Ciliated : Have	 clilia	 to	 move 	 food	 into	 gullet 	 and	 help	 in	 locomo tion.	
e.g., Paramoecium.
Sporozoans : Have	 infective 	 spore	 like 	 stage	 in	 life	 cycle,	 e.g., 
Plasmodium 	which	causes	malaria.
Kingdom Fungi
1. Heterotrophic	or ganisms
2. Non 	 chlorpohyllous 	hyphae
3. Network	of	hyphae	called	mycelium
4. Hyphae 	 which	 have	 multinucleated 	 cytoplasm	 are	 called	 coenocytic	 hyphae
5. Cell 	wall	of	chitin	and 	polysaccharides
6. Cosmopolitan. 	Grow 	in	warm 	and	humid	places.
7. Saprophytic, 	 parasitic, 	 symbiotic 	 (Lichen	 and	 Mycorrhiza)	e.g., Puccinia,
(wheat 	rust 	disease), 	Penicillium, Y east 	(unicellular 	fungus).
8. Reproduction 	 can	 take	 place 	 by	 vegetative	 means	 fragmentation,	 fission
and	 budding.	 Asexual 	 reproduction	 by	 spores–conidia, 	 sporangiospores	 or
zoospores. 	 Sexual 	 reproduction 	 by 	 Oospores,	 ascospores 	 and	 basidiospore s–
produced 	in	fruiting	bodies.
9. Sexual cycle involves 3 steps :
 (i)	 Plasmogamy	(fusion 	of	Protoplasms.)
(ii)	 Karyogamy	(fusion	of		two	nuclei.)
(iii)	 Meiosis 	in	zygote	resulting	in	haploid	spores.
10. Dikaryophase 	 is 	 a	 condition	 of	 having	 dikaryon	 in	 an	 intervening 	 dikaryotic
stage 	(n	+	n	i.e., 	 two	 nuclei	 per	 cell) 	 between	 plasmogamy	 and	 karyogamy
in 	fungi	like	ascomycetes 	and	basidiomycetes.
Classes of Fungi
 (i) Phycomycetes :
 ? grow	on	decaying	wood	or	as 	obligate	parasites 	on	plants
 ? Mycelium	aseptate 	and	coenocytic
 ? Spores	produced	endogenously 	in	sporangium.
 ? Asexual 	reproduction 	by	Zoospores 	or	 Aplanospores
 ? Zygospores	are	formed 	by	the	fusion 	of	gametes.
e.g., Rhizopus, Albugo, Mucor
24
(ii) Ascomycetes :
 ? also	known	as	‘sac	fungi’
 ? Are	 saprophytic,	 decomposers, 	 parasitic	 or	 coprophilous	 (growing	 on
dung).
 ? Mycelium	branched 	and	septate
 ? Asexual 	 spores	 are 	 called	 conidia	 produced	 exogenously	 on	 the
conidiophores.
Sexual 	 spores 	 are	 called	 ascospores 	 produced 	 endogenously 	 in	 ascus, 	 produced
inside	fruiting 	body	called	 Ascocarp.
e.g., Aspergillus, Neurospora, Saccharomyces (Unicellular fungi),
Claviceps, morels, truffles 
 (iii) Basidiomycetes :
 ? Mycelium	septate	and	branched.
 ? Generally	asexual	spores 	are	not		found.
 ? V egetative 	reproduction 	by	fragmentation.
 ? Se xua l 	 re produc t i on 	 by	 fusi on	 of	 ve ge t a t i ve 	 or	 som a t i c 	 c e l l s 	 t o	 form 	 ba si di um
produced 	in 	basidiocarp.
 ? Basidium	produces 	four	basidiospores	exogenously 	after	meiosis.
e.g., Agaricus, Ustilago, Puccinia
 (iv) Deuteromycetes :
 ? Called	 as	 ‘Fungi 	 Imperfecti’ 	 	 as	 sexual	 form	 (perfect 	 stage)	 is	 not	 known	 for
them.
 ? Once	 sexual 	 form	 is	 discovered	 the 	 member 	 is	 moved	 to	 Ascomycetes	 or
Basidiomycetes.
 ? Mycelium	is 	septate	and 	branched.
 ? Are	saprophytic	parasitic	or	decomposers.
e.g., Alternaria, Colletotrichum, Trichoderma.
Viruses :
? They	did 	not	find	a	place	in 	biological	classification.
? Not	truly	living.